Lewis is also convinced the 40-year-old would never have lost to Tyson Fury with Steward in his corner, and that Klitschko’s biggest challenge in preparing for his April 29 fight with Joshua comes in shifting his focus from Fury. Steward was widely considered the greatest trainer in boxing history at the point of his death, from complications following surgery for the stomach condition diverticulosis, at the age of 68 in October 2012.